The feller buncher attachment for a timber harvesting tractor conventionally has a horizontally rotating circular saw, or a horizontally operating shear, mounted in the attachment frame. In the rotary saw embodiment, the saw disc is mounted on the lower end of a vertical spindle supported for rotation in a housing on the attachment frame. A hydraulic motor mounted on top of the housing rotates the spindle and, accordingly, the saw disc.
In such a conventional bunching saw assembly, the spindle is supported in upper and lower bearings seated within the saw assembly housing. A vertically elongated cavity within the housing surrounds the shaft and contains the upper and lower bearings. The base of a drive motor body covers the top of the cavity and a main housing seal forms the bottom of the cavity. To lubricate the bearings, a grease zerk fitting is conventionally provided in the housing above the upper bearing and another is provided between the upper and lower bearings.
The amount of grease injected into the various cavities within the vertically elongated cavity is prescribed by the manufacturer and is based on specified hourly or daily consumption rates. Because the amount of grease consumed varies with operating conditions, more or less grease than that prescribed by the manufacturer may be consumed, however. If consumption is greater than anticipated, inadequate lubrication eventually results and bearing failure is possible.
Problems also result if grease consumption is less than anticipated. The cavities will then be overfilled by manufacturer-dictated lubrication. All cavities within the housing tend to fill before grease is forced out of relief fittings normally provided to permit air to escape during grease injection. This excess of grease acts as an insulator, causing the operating temperature of bearings to rise and reducing their service life. Since the relief fittings are conventionally located where they cannot be seen, the operator doesn't know that the cavities are overfilled.
In addition to the aforedescribed problems associated with conventional systems, a substantial amount of grease is required to fill the entire cavity. This increases operation costs.